The present invention relates to a TiC-based cermet body with a reduced amount of pores and an increased hardness and also a method of making such cermet body.
Sintered bodies like cutting tool inserts, etc., are usually made from materials containing cemented carbides or titanium based carbide or carbonitride alloys, often referred to as cermets.
Materials like cermets usually contain one or more hard constituents such as carbides or carbonitrides of, e.g., tungsten, titanium, tantalum, niobium, etc., together with a binder phase. Depending on composition and grain size, a wide range of materials combining hardness and toughness can be used in many applications, for instance in metal cutting tools, in wear parts, etc. The sintered bodies are made by techniques common in powder metallurgy like milling, granulation, compaction and sintering. The binder phase in cermets is usually Co, Fe or Ni or mixtures thereof.
The first cermet materials developed were TiC-based. The cermet materials were then further developed and in the eighties, carbonitride-based cermets were introduced and a large part of the cermet materials developed since then are carbonitride-based.
For conventional cemented carbide, i.e., WC—Co based, fine grained particles after sintering can be obtained by adding chromium. However, when adding chromium to a carbonitride based cermet, little or no effect on the grain size can be seen.
CN 1865477 A discloses a guide roll, spool or valve seat of a TiC—WC based alloy comprising 30-60 wt % TiC, 15-55 wt % WC, 0-3 wt % Ta, 0-3 wt % Cr and 10-30 wt % of a binder phase being Co and Ni.
U.S. Pat. No. 7,217,390 describes a method of making an ultra-fine TiC-based cermet by obtaining mechano-chemical synthesis, e.g., high-energy ball-milling of powders of Ti, transition metal (TM), Co and/or Ni powders and carbon powders. Alternatively the Ti and transitional metals can be added as carbides. The transition metal, TM, can be at least one element of Mo, W, Nb, V or Cr. The high-energy ball-milling will form (Ti,TM)C.
However, high-energy ball-milling is a complicated process and it would be beneficial to be able to provide a fine-grained TiC-based cermet using conventional techniques.